1. Field of the Invention
The present invention relates to desalination systems, and particularly to an evaporative desalination system that produces a substantially uniform density of condensed water vapor on the condensation surface.
2. Description of the Related Art
Recently, great interest has been focused on the technique of desalinating seawater by using solar energy. FIG. 6 is a schematic view of a conventional desalination apparatus 100 that uses solar energy, which is commonly known as a “basin-type solar heat distiller”. The desalination apparatus 100 has a basin 102 for holding raw water W (e.g., sea water) and an air shield 103 that covers the basin 102 and is permeable to sunlight S. The outer surface of the air shield 103 is used as a radiating part 106. In the desalination apparatus 100 of FIG. 6, the raw water W in the basin 102 is heated with sunlight S to generate water vapor 105. The water vapor 105 is cooled and condensed on the inner surface of the air shield 103, and thus distilled water 107 is obtained.
In the simplified diagram of FIG. 3, a conventional tray T holds the raw water W, the evaporated water condensing on a generalized condensing surface C. FIG. 3 illustrates the disparity between the differing heights H1 and H2 between the surface of water W and the different locations on the condensing surface C in a more dramatic fashion than FIG. 6. This exaggeration is provided to illustrate the differences between the density of condensed water vapor CW1 (formed at height H1) and the density of condensed water vapor CW2 (formed at height H2). The density of CW2 is much greater than CW1 due to the relatively small distance of travel of the evaporated water. It would be desirable to provide a desalination system in which the density of water vapor condensation on the condenser surface is substantially equivalent across the entire surface area of the condenser surface.
Thus, an evaporative desalination system solving the aforementioned problems is desired.